Incandescent electric lamp.



No. 821,056. IATENTED MAY 22, 1906. H. C. PARKER. .INCANDESCENI ELECTRIC LAMP.

APPLICATION FILED APR.21,1904.

WITNESSES.- NV/ENTOR.

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HERSGHEL C. PARKER, OF NEW YORK, N. Y., ASSIGNOR TO PARKER-CLARK ELECTRIC COMPANY, OF JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY.

INCANDESCENLT ELECTRIC LAMP.

Specification of Letters Patent.

Patented May 22, 1906.

Application filed April 21, 1904.. Serial No. 204,170.

To all whom it may concern:

Be it known that I, HERSCHEL O. PARKER, of New York, in the county of Kings and State of New York, have invented a new and Improved Incandescent Electric Lamp, of which the following is a full, clear, and exact description.

My invention relates to improvements in incandescent electric lamps; and the object of my invention is to produce a cheap and simple lamp which is very durable and which consists in the main of a pencil formed chiefly of refractory non-conducting substance, but with a small percentage of conductive substance mixed therewith, the whole being arranged and combined so that a current will pass through the pencil when the latter is cold and will quickly raise the same to a bri ht incandescence.

l have found by experiments that by mingling some refractory non-conductive substance, such as thorium oxid or carborundum, with a small percentage of a refractory conductor, such as graphite, and shaping the mass into a pencil, the latter being preferably compressed, I can cause a current to pass through the pencil when the latter is cold, and it will still have sufficient resistance to cause the pencil to be raised to a high heat, and thus an eflicient lamp is provided. It is probable that other substances than the thorium oxid and carborundum may be used;

but the substances must be of such a nature that when mixed with the conductor they will produce a light-giving pencil and not one which will merely glow under the influence of the current.

With these ends in view my invention consists of an electric lamp, the construction of which will be hereinafter described and claimed.

Reference is to be had to the accompanying drawings, forming a part of this specification, in which similar figures of reference indicate corresponding parts in both views.

Figure 1 is a detail elevation, with the terminals in section, of the simplest form of the lamp. Fig. 2 is a longitudinalsection, with the pencil in elevation, of the lamp provided with an inclosing transparent or translucent cylinder.

nary heating,

The principal portion of my lamp consists of the pencil 10 and its conducting-terminals 11. The pencil 10 is made, as above remarked, preferably of thorium oxid or carborundum mixed with some good refractory conductor. To get the best results, there should be approximately three or four parts of the oxid to one of the conductor, and for the latter graphite works perfectly. To form the pencil, the ingredients are reduced to a fine powder and thoroughly mingled and the parts may be held together by a suit able binder forming a sort of dough which can be forced through a die to make the pencil of the right size and the pencil can be cut into the requisite lengths and dried and baked. As a result I produce a pencil which will conduct the current when cold, thus obviating the necessity of providing a prelimiand at the same time the pencil is of comparatively high resistance and of such a nature that it willnot flame, but will glow with a bright incandescence when sealed within a tube from which the air is partially exhausted.

The terminals 11 are preferably of graphite and receive the leading-in wires 12, the terminals being also arranged so as to fit snugly like stoppers in a transparent or translucent tube 13, which is preferably of glass, as the air-gap between the tube and the pencil 10 is sufficient to prevent the lass from slagging. The graphite 11 is he d in place by a suitable cement or seal, as 14. The air can be exhausted from the tube in any usual way, and this can be done easily by leaving a vent in the glass, heating the pencil to incandescence, thus expelling the air and gases and sealing the vent while the pencil is still hot.

I do not wish to limit the invention to the use of the ingredients named, as other stable oxids or "refractory materials can be substituted for the said ingredients; but they must be of such a nature that a firm hard pencil can be formed and also of such a nature that the constituents will not unite chemically at the temperature of incandescence or disinte grate at the same temperature.

It will be understood that the terminals 1.1 may be independent blocks of graphite, as shown, or the pencil 10 can have enlarged ends corresponding in shape to the parts 11, so as to fill the-tube 13 near the ends, the result being the same in either casein other words, the parts 10 and 11 forming really the body portion of the lamp.

llaving thus fully described my invention, I claim as new and desire to secure by Letters Patent 1. An incandescent electric lamp comprisin a transparent tube, a pencil of mingled rel rac'tory conducting and non-conductin materials held longitudinally in the tube, an terminals of larger cross-section than the pencil, said terminals filling the tube ends and forming a support for the pencil so as to make a gap between the pencilsand the sides of the tube;

2. An incandescent electric lamp 'compris in a transparent tube, a (pencil of mingled re actory conducting an non-conducting materials arranged longitudinally in the tube so as to leave a gap between itself and the tube end, terminals for the pencil, said terminals filling and closing the tube, and a seal for the ends of the tube.

' .HERSCHEL O. PARKER. 

